In a digital single lens reflex camera, an imaging element with a large element size is installed. As for this kind of imaging element, the size which a photolithography process can handle at one time is limited due to a relation of production equipment (a stepper etc.) of a semi-conductor. Therefore, a manufacturing process of the imaging element performs a segment exposure with the process divided in multiple times while shifting an exposure region as required. The imaging element having this multicycle segment exposure performed thereon has a possibility that the property may vary in each region of the segment exposure. Due to this property variation, signal irregularity is caused in an image data which the imaging element generates.
Patent Document 1 is known as a technology which corrects the signal irregularity of this kind. This conventional technology, by multiplying a pixel direction orthogonal to a boundary line of the segment exposure by an identical correction value uniformly, corrects a signal level difference caused in the boundary line (for example, FIG. 3 of Patent Document 1). Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-112423.